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Abstract

An Oriental Mealybug (Pseudococcus lilacinus Ckll.) (Hemiptera) and its Insect Enemies.

Abstract

The greater part of this paper comprises notes on insect parasites and predators of Pseudococcus lilacinus, Ckll., collected in 1936-37 in the Philippines, the Netherlands Indies, Ceylon and southern India in an attempt to discover species suitable for introduction into Kenya Colony against P. kenyae, Le Pelley, on coffee [R.A.E., A 27 665]. The synonymy of P. lilacinus (crotonis, Green, tayabanus, Ckll.) is discussed, and reasons are given for disagreeing with Betrem's views [26 608] and for regarding P. kenyae as distinct from it. In addition to the countries surveyed, it also occurs in Malaya, where it is rare, and Formosa, and is restricted to altitudes up to approximately 3, 000 ft., whereas P. kenyae occurs only in parts of Uganda and a small lake shore area in Tanganyika Territo-, where it appears to be indigenous and supports many parasites, and the part of Kenya into which it has been introduced. It normally exists at high altitudes. The chief food-plants of P. lilacinus include Annona muricata, guava, cacao, Ceibapentandra and species of Bauhinia, Spondias and Erythrina. It is not often found on Citrus, and coffee usually grows above its altitude range, though it has been recorded on it in Formosa. A list is given of 13 new food-plants in the Philippines and 3 in southern India. The mealybug is attended by many ants, and notes are given on the distribution and frequency of the various species observed.
P. lilacinus was locally abundant at Los Baños in the Philippines, where its most important predators were the Lycaenid, Spalgis epius, Westw., and the Coccinellid, Platynaspis stictica, Crotch, subsp. philippensis, Korchefsky. The latter was always present, sometimes in large numbers, in collections from guava. Other Coccinellids that attacked the mealybug comprised a species tentatively identified as Scymnus (Nephus) oblongosignatus, Muls., which was common in one collection from guava and was parasitized by Homalotylus sp., and Aspidimerus tristis, Weise, and an unidentified species of Scymnus, which were not abundant. Coccodiplosis pseudococci, de Meij., appeared to be an important predator, but the larvae in the cocoons were at times heavily parasitized by a species of Ceraphron (Calliceras). As many as six larvae of this Cecidomyiid attacked a single adult of P. lilacinus, and evidence was obtained that the mealybug is killed by the attack. Larvae of an unidentified predacious Cecidomyiid were also common. Eleven Encyrtid parasites were associated with P. lilacinus, of which at least three, including a species of A chrysopophagus, are probably hyperparasites. Only three of the others were of any importance, and the chief of these was Pseudaphycus orientalis, Ferrière. Up to 30 adults of this species emerged from a single host. Development from oviposition to adult emergence lasted 19-21 days at a mean temperature of about 75°F. Pairing and oviposition occurred soon after emergence, and adults fed on honey survived in the laboratory for about 16 days. This parasite practically eliminated the mealybug on heavily-infested small trees of Bauhinia.monandra in little over a month, but was not found in numbers on plants other than Bauhinia. Anagyrus lilacini, Ferrière, occurred in most collections of the mealybug from various food-plants, and, though never very numerous, appeared to be of some value, even where P. orientalis was dominant. Development lasted 20-24 days at about 75°F., and adults fed on honey survived for up to 30 days. Taftia saissetiae, Gah., was common and is thought to be a primary parasite. Others included Aphycus sp. and another species of Anagyrus, both obtained in small numbers.
P. li lacinus is common in the Netherlands Indies. Its chief predators there are Spalgis epius, Scymnus apiciflavus, Motsch., which is parasitized by Homalotylus sp., and Coccodiplosis pseudococci, which is parasitized by a species of Ceraphron, apparently the same as that found in the Philippines, and it is also attacked by another Cecidomyiid and a species of Eublemma. The most important parasites are Anagyrus spp. and a species of Taftia that also attacked P. lepelleyi, Betrem. Of the species of Anagyrus, the most important in Java is probably identical with the undetermined Philippine species. It appears to be capable of completely destroying infestations of P. lilacinus.
In Ceylon, P. lilacinus is common on Annona muricata and cacao but is less abundant than in Java. Spalgis epius was fairly common, and other predators comprised four Coccinellids, none of which is of importance, , and a Cecidomyiid, probably Coccodiplosis pseudococci, that was attacked by a parasite similar to the Philippine Ceraphron. A species of Anagyrus and another fairly common Encyrtid parasitized the mealybug.
In southern India, P. lilacinus was common only at Coimbatore, but was collected at four other localities from which it had not previously been recorded. Its natural enemies comprised 5. epius and three Coccinellids, including Hyper-aspts maindroni, Sic., and a species tentatively determined as Scymnus (Nephus) severini, Weise, which were of some importance, Eublemma sp., Leucopis luteicornis, Malloch, two other Cecidomyiids, a species of Anagyrus, and another Encyrtid, possibly Tetracnemus indicus, Ram. Ayyar, which was common.
Information on the abundance of the various species in the different localities is summarised in a table.